Place the egg yolks, sugar and salt into a deep, medium sized saucepan and whisk into a thick paste.
Place the oat milk and double cream alternative into a large jug and whisk briefly. Pour around 2tbsp into the egg mixture and whisk. Attach a candy thermometer to the side of the pan and place over a low heat.
Heat gently, gradually adding in the milk/cream mixture while you whisk continuously, to ensure no lumps. I add around 1/4 cup of milk at a time. It needs to be gradual in both the heating and the adding of the milk, so as not to scramble the eggs!
Continue whisking and adding the milk until all of it is in the saucepan. Then switch to a wooden spoon and continue to heat. The mixture needs to first reach 160F/70C to ensure the eggs are safe. You will then start to feel it thicken slightly.
I heat my mixture to 180F/82C. This is the point where I find it doesn't thicken anymore, the eggs are safe and we're far enough away from boiling the mixture as we do not want that. Don't be tempted to whack the heat up either, it needs to be gentle. It will take at least 20 minutes, maybe 25 to get to 180F/82C.
Once the eggnog is at the correct temperature, remove from the heat, remove the candy thermometer and add in the vanilla extract. Stir until combined and then leave to cool for 15 minutes, just so it's not hot for the next step.
After 15 minutes, take a piece of cling film and press it gently into the top of the eggnog, so it's touching it and the excess cling film comes up the sides of the pan to create a seal. This will stop a film developing on top of the eggnog. Leave to cool completely in the pan.
Once cool, transfer to a pitcher/carafe and cover the top with cling film. Store in the fridge for up to 3 days. If you are adding alcohol to this recipe, it will keep for longer.
To serve: pour chilled Dairy Free Eggnog into a glass and grate some fresh nutmeg onto the top. Alternatively, if you're like me and never have fresh nutmeg, sprinkle some ground nutmeg on top.